CMOS temperature sensors - concepts, state-of-the-art and prospects

Abstract

The paper reviews the state-of-the-art in IC temperature sensors. It starts by revisiting the semiconductor theory of thermodiodes and thermotransistors, continues with the introduction of IC temperature sensors, the concepts of VPTAT - voltage proportional to absolute temperature and IPTAT (current proportional to absolute temperature) and discusses the possibility of use of parasitic bipolar transistors as temperature sensors in pure CMOS technology. The next section demonstrates the very high operating temperature of a dasiaspecialpsila thermodiode, well beyond the typical IC silicon junction temperature. This is achieved with a diode embedded in an SOI CMOS micro-hotplate. A discussion on the temperature limits of integrated temperature sensors is also given. The final section outlines the prospects of IC temperature sensors.